Rhoiconeis pagoensis Lobban, 2015

Lobban, Christopher S., 2015, Benthic marine diatom flora of Guam: new records, redescription of Psammodictyon pustulatum n. comb., n. stat., and three new species (Colliculoamphora gabgabensis, Lauderia excentrica, and Rhoiconeis pagoensis), Micronesica 2015 (2), pp. 1-49 : 14

publication ID

https://doi.org/ 10.5281/zenodo.12117576

DOI

https://doi.org/10.5281/zenodo.12576027

persistent identifier

https://treatment.plazi.org/id/03826143-FF96-8174-FF34-FE071591FB10

treatment provided by

Felipe

scientific name

Rhoiconeis pagoensis Lobban
status

sp. nov.

Rhoiconeis pagoensis Lobban n. sp. Figs 131–138 View Figures 127–138

NAVICULALES Bessey : Naviculaceae Kützing

Samples: GU7X-2, GU7X-7

Dimensions: Length 16–49 µm, width 6.7–7.9 µm; striae 16–22 in 10 µm

Diagnosis: Differing from the other two species in the stria density.

Holotype: Slide # 1319 from GU7X-7, Fig. 133 View Figures 127–138 . Deposited at California Academy of Sciences , accession # 627426 slide # 220342.

Type locality: Pago Bay , Guam, 13°25'40" N, 144°47'57" E, on shore in University of Guam Marine Laboratory seawater outfall stream, collected by C. Lobban, 3 June 2013 GoogleMaps .

Paratypes: Slides #1265, 1266, 1270–1272 in UOG Diatom Herbarium.

Etymology: named for the type locality, Pago Bay, itself probably from pagu, the Chamorro name for the tree Hibiscus tiliaceus L., whose bark was traditionally used to make rope.

Description: Live cells motile, two plastids lying along the girdle faces as in Navicula ( Fig. 131, 132 View Figures 127–138 ). Frustules flexed in girdle view, the central areas of the two usually different, with the broader area on the concave side ( Figs 136, 137 View Figures 127–138 ). Striae lineate, radiate except for short ones bordering the central area ( Figs 135, 137 View Figures 127–138 ). Valvocopula in two segments, with a sigmoid junction near one apex

( Fig. 138 View Figures 127–138 ); the smaller segment reminiscent of the end plate in Rhabdonema arcuata ( Pocock & Cox 1982) . There were slight differences in stria count common between apices and center, the two apices and the two valves. Frustules did not come apart even after double acid cleaning and I was not able to get SEM of the internal valve face.

Comments: Samples were collected over several days from a diatom bloom in an outfall stream from the U. Guam Marine Laboratory seawater system. The bloom developed soon after the seawater flow was restarted, epiphytic on a population of the siphonous green alga Trichosolen sp. , itself known to be rare except for blooming after a major disturbance ( Lobban & Tsuda 2003).

Rhoiconeis Grunow was resurrected by Medlin (1985) and currently includes two species ( Table 1 View Table 1 ). The genus is characterized by naviculoid frustules flexed in girdle view and having lineate striae and internal siliceous sheets joining the outer parts of the interstriae. There is a distinctive pattern in the girdle bands, with a segmented valvocopula and two pleural bands, as shown in Medlin (1985, fig. 38; compare with my Fig. 138 View Figures 127–138 ). In Rhoiconeis both valves are raphid, in contrast to Achnanthes View in CoL ; isopolar, in contrast to Rhoicosphenia View in CoL ; and distinguished from Campylopyxis View in CoL by the pores, girdle bands, and internal valve features. Both known species of Rhoiconeis have radiate, lineate striae and slightly different central areas on the convex and concave valves. Thus, the present material can be positively identified as Rhoiconeis even without good internal views, and can be distinguished from the other species on the basis of valve size and stria density ( Table 1 View Table 1 ).

Kingdom

Chromista

Phylum

Ochrophyta

Class

Bacillariophyceae

Order

Naviculales

Family

Naviculaceae

Genus

Rhoiconeis

Loc

Rhoiconeis pagoensis Lobban

Lobban, Christopher S. 2015
2015
Loc

Campylopyxis

L.K.Medlin 1985
1985
Loc

Rhoicosphenia

A.Grunow 1860
1860
Loc

Achnanthes

Bory 1822
1822
GBIF Dataset (for parent article) Darwin Core Archive (for parent article) View in SIBiLS Plain XML RDF